Delaying Graduation Date for IB SA?

Hi

I'm currently a rising junior at a target school, and I only realized recently (like last month lol) that I want to go into IB. I applied to a few places (BBs, EBs) within the last week or two. Although I have already applied to a few places, I'm not optimistic about my chances in landing a SA for summer 2020 because I'm not majoring in finance/econ/accounting so I have very limited knowledge and I haven't even begin studying for IB interviews (I have the M&I investment banking guide).

I'm thinking about delaying my graduation by a semester because that would give me time to get more finance experience (only have one right now and it's not even that good), higher GPA, opportunities to network more (haven't even networked at all coz I didn't know i wanted finance), as well as give me more time to study for the technicals. Also, by delaying my graduation, I just mean sacrificing a semester to do an internship and make up for that semester.

Do you guys think that delaying graduation is a solid plan in my case?

How long should it take to study the technicals (for someone with little exposure to finance/accounting/econ)?

Lastly, if anyone has ever used the mergers & inquisitions IB interview guide, what is the best way to use that guide to prepare for interviews since I don't exactly have alot of time before interviews/superdays (prob like 1-2 months left)?

Any help is much appreciated!

Thanks